San Diego writer Amy Wallen clearly remembered a trip her family had taken to a pre-Inca graveyard in Peru when she was eight. She and her older brother were playing among miles of sand dunes when he found a human skull. Soon after, her parents unearthed a gravesite with an intact body.

Wallen’s father was a geologist working for oil companies in the 1970s, and his work took them to Nigeria, Peru and Bolivia. But in trying to fill in the gaps of her memories by talking with her parents recently, she realized that much of what she recalled was wrong. Her brother was in another country at the time. Her mother does not remember a body at all. Wallen, who teaches creative writing at UC San Diego Extension, was hesitant to probe further.

“I am afraid of what I will find out, but I am caught in this tug-of-war: the family story and what now looks like a crime,” she wrote in her new memoir, “When We Were Ghouls.”

Wallen’s eventual research led her to re-examine her childhood abroad. She joins KPBS Midday Edition on Tuesday with more on the uncertainty of memory.